Tony Abbott has left open the option of barring Russian president Vladimir Putin from attending the G20 summit in Brisbane in November.

While no decision has yet been taken, Mr Abbott appeared to step up his rhetoric over Russian policy in Ukraine branding it "bullying" and "interference" which must stop, just days after the Prime Minister played down using the G20 to apply pressure on Mr Putin.

The shift followed harsh condemnation by Canadian Prime Minister Stephen Harper of Russian annexation of Crimea and Russian support for rebels attempting to mount a civil war against the government led by new president, Petro Poroshenko.

Mr Abbott, who is due to meet Mr Harper for much of Tuesday in Ottawa, backed up the Canadian's view that Moscow was behaving in a manner that amounted to a slow motion invasion of another country.

Prime Minister Tony Abbott has left door open to barring Russian leader Vladimir Putin from the G20. Photo: Andrew Meares

Those comments came despite the potential negative implications for extensive Russian/Canadian energy ties.

Canada has now marked itself out as one of the most forthright critics of the Putin regime, with other nations such as Britain, Germany, and France, backing trade sanctions in principle to drag Russia back within the international rules, but then holding private talks with Moscow to protect their own particular commercial links.

Just days ago in France where Messrs Abbott, Putin, Harper and Poroshenko had shared the public stage at D-Day commemorations, Mr Abbott described the G20 meeting as primarily economic and, therefore, not the forum to involve itself with security matters such as Ukraine's sovereignty.

But asked about Mr Harper's comments while visiting the Canadian capital, Mr Abbott hedged arguing Mr Putin's attendance in Brisbane was a matter about which it was right to "wait and see".

"Well they're very forthright remarks and I think that they're perfectly appropriate remarks for the Canadian Prime Minister to make," Mr Abbott said.

"Let's not minimise the affront to international stability and the affront to the ordinary norms of behaviour between nations which Russia has been responsible for, I mean, it's bitten off the Crimea, it's obviously interfering in Ukraine and this should stop, this should stop, no country has a right to bully another country just because it can."

Pressed on whether allowing Russia to attend provided some comfort to Mr Putin when others were condemning his action, Mr Abbott argued for time to allow events to play out.

"Well let's wait and see what happens in the next few months," he said.

The question of Russia's attendance at the G20 – now the premier international economic grouping – has been hotly debated in recent weeks as countries have looked to what actions should be taken to send a clear message to Moscow that the use of force in international affairs is unacceptable.

The G8 met as the G7 last week in Brussels after Russia was suspended.